Looking at the assembly the gear is a simple quadrant, the small drive gear follows an arc defined by the pin with the circlip. That being the case you need to find the gear module - as it’s from a Merc it will be metric - then obtain a standard gear from somewhere like HPC and cut the quadrant from that.Here is the other good side showing the drive gearView attachment 151786
Here is the other good side showing the drive gear
What's a slow Sunday?